Telephone system



Patented Mar. 17, 1931,

oni'rso STATES PATENT oFFIcE JOHN ELLIS OSTLINE, OF LIVERPOOL, ENGLAND, ASSIGNOR TO ASSOCIATED TELEPHONE AND TELEGIEAPH COMPANY, OF KANSAS CITY, MISSOURI, A CORPORATION OF DELA- WARE TELEPHONE SYSTEM Application filed September 15, 1928, Serial No. 306,178, and in Great Britain October 10, 1927.

This invention relates to improvements in semiautomatic telephone systems, and particularly concerns improved means for establishing connections between manual and automatic subscribers, in a system in which an operator is provided with facilities for operating automatic equipment.

Calls of this class have usually been handled by one of two methods, either by furnishing the B operator with special equipment to set up connections in automatic oflices, the connection being extended to the B operator in the usual manner, or by equipping the A positions with direct outgoing junctions to the automatic oflices and providing means whereby the A operators can dial the required number. Experience has shown that except in special cases this latter method is preferable and the usual arrangement for providing these facilities is to insert a key in the calling end ofthe cord circuit which will disconnect theanswering end and connect an impulse sender across the calling end. The calling plug is then inserted in a junction to the required automatic exchange and the operator manipulates the dial to obtain the required number. It will be appreciated that this method involves changes to all the cord circuits with its consequent labour and inconvenience, particularly if trafiic is heavy. The present invention aims at providing these facilities without alterations or additions to the cord circuit itself, the dialling equipment being added to the existing operators speaking circuit without altering the present equipment or its functioning.

According to one feature of the invention in a system having arrangements whereby an A operator is enabled to complete connections from cord circuits over automaticnumercial switches by means of a dial switch adapted to be associated with any desired cord circuit by means of a key individual thereto, during impulse sending the normal connections of the supervisory and battery feeding relays to the speaking conductors of both the, calling and answering ends of the cord remain unaltered.

Another feature of the invention is that impulses are sent by the intermittent application of earth to the two speaking leads connected together, said application serving to effect the de-encrgization of a relay at the outgoing end of a line extending to an automatic switch.

The invention will be better appreciated from the following des .:ription of one method of carrying it into effect which should be taken in conjunction with the accompanying drawing. It will be understood however that this is given by way of example only and that detail modifications to the circuits shown could be made by those skilled in the art without exceeding the scope of the invention.

In the arrangement considered the apparatus for the circuit comprises junction relay sets which are connected in the out going junctions to the automatic otlice, the junctions terminating in the usual manner in junction multiple jacks, and equipment common to a position for introducing the dial into the speaking leads of the various cord circuits. This equipment consists of two relays which may be of the same type as usually used in manual positions, and a dial switch, a supervisory lamp and a release key of the push button type which is mount ed near the dial on the operators key shelf.

Referring to the drawing, the upper portion shows part of a typical staiulard cord circuit CC, together with the standard operators speaking circuit SC, and the dialling circuit DC, the lGllQ 'S associated. with the dialling circuit being mounted in or near the position and the calling device, key and lam 011 the keyboard. The lower portion of t edrawing shows the equipment which is associated with each outgoing junction accessible from the A operators position. The outgoing junctions to the various automatic ofiices appear in the regular junction multiple in the usual manner. The iii-st jack of each group of say ten junctions to any one exchange is wired in a special manner and will be termed a master jack; such a jack is shown in the drawin When the A operator receives a call from a manual subscriber, she will insert the" anioii swering plug 18 of the cord circuit CC into the calling subscribers jack and operate the speaking key 16. After ascertaining the number wanted, which in this case is assumed to be in an automatic office, she takes up the calling plug 19 and tests the first master jack of the junction group outgoing to the desired automatic ofiice. If the junction connected to this jack is busy, she will receive the usual busy test, and may in addition receive a special indication e. g. a tone, which indicates that all the junctions associated with this master jack are busy. Hence if the operator receives this tone, she proceeds to test the next master jack. It now she only receives the usual busy signal,

this indicates that'atleast one junction within this group is available, and she therefore tests the junctions in turn until an idle one is found.

When the operator finds a free junction for instance that comprising conductors 60 and 61, sheinserts the calling plug 19 into the associated jack 20. Sleeve relay 37 of the junction repeater R is thus operated and at armature 47 connects the impedance relay 39 and shunt field relay 40 across the conductors 60 and 61 extending to the automatic ofiice, whereupon relay 39 operates. The operation of sleeve relay 37 also at armature 45 polarizes the shunt field relay 40, and at armature 46 prepares a holding circuit for relays 41 and 42. Relay 37 also operates armature 44 thereby closing a pointin the circuit for connecting the tone source over conductor 62 to the sleeve conductor "33. This circuit will be completed when all the sleeve relays of the group controlled by the master jack are operated so that when the operator touches the tip of a calling plug on the. sleeve of jack 20 she will hear a tone indicating that all the junctions of the particular group are busy. At this time relay 11 is feeding out battery on the ring side and relay 10 is feedingout earth on the tip side of the junction, but this does not operate any relays in the junction relay set.

Leaving the speaking key 16 operated, the operator now commences to dial the first digit of the wanted-number. As soon as she operates the dial, ofi-normal springs 25 connect battery to relay 23 in the dialling circuit DO, whereupon relay 23 operates-and at armature 3Q completes the circuit for re-. lay 22 from earth on key 26, armature 30,

winding of relay 2,2 to battery. The opera tion of relay 22 connects the speaking leads together, and al o. to impulse springs 24 of the dial. Owing to this connection, current will now flow from impedance relay 11 in the cord circuit to the junction relay set R over'the tip conductor 31, armature 56 and relay 43 to earthy. Relay 43 is of special design hat it is capable of opera ng wi h a small. arneuntofcurrent and releasing at high speed when that current is interrupted or shunted. Relay 43 operates at this time and completes a circuit from earth by way of armatures 52, 59 and 54, winding of relay 41 to battery. Relay 41 operates its armature 53 quickly and thereby locks itself to earth on armature 46. Relay 41 also at armatures 52 and 54 connects the armature 59 of impulsing relay 43 across the conduc: tors 60 and 61, anddisconnects the shunt field relay 40 and impedance relay 39 and at armature 51 completes a circuit for relay 38, which is however at present short-circuited. v

lVhen the operator releases the dial, the normally open impulse springs 24 will make contact a number of times corresponding to, the number dialled. This will place an earth on the short-circuited speaking leads and.

this earth will therefore shunt out relay 43 causing it to release and open the circuit to the selector in the automatic ofiice anumber of times in accordance with the digit dialled. When the calling device has returned to normal, relay 23 is held by way of resting springs 25 of the dial to battery through relay 11 in the cord circuit, relay 23 being designed so as to. require only a very small holding current. This is because relay 11 is at this time supplying current also to relays 10 and 43. The remaining digits are now dialled in the same manner as the first digit and they are repeated by relay 43 in the same way. It will be noted that the an swering end of the cord is not disconnected during dialling but the subscriber will not receive any objectionable clicks as the speaking pair is. shortscircuited during the trans mission of impulses.

When the operator has finished dialling the speaking key 16 is restored whereupon relays 22 and 23, de-energize and re-connect the leads 8 and 19 to the operators circuit. Relay 38 now operates in series with relays 11 and 10, and at armature 48 energizes relay 42. This relay operates armature 58 quickly thus locking itself to armature 46 and at armature 56 disconnects impulsing relay 43, holds the connection to the automatic office at armature 55 by way of impedance relay 39 and shunt field relay 40 and armature 47 of sleeve relay 37, and at armature 57 brings down relay 38 and alters its circuits so that it can be used to give supervision to the A operators cord circuit. The calling manual subscriber should now receive ringing tone to indicate the ringing of the called subscribers bell and when the called subscriber answers, shunt field relay 40 operates due to the reversal of current. Relay 40'thereupon at armature 50 connects relay 38 across tip and ring conductors 31 and 32 thus operating relay 10 in the cord circuit to give the usual supervision at armature 14'.

When the called party hangsup at the end of the conversation, relay 40 again de'energizes and at armature 50 opens the circuit of relay 10 which de-energizes to give clearing supervision. When the operator removes the plug 19 from the jack 20 sleeve relay 37 is de energized and at armature 47 opens the outgoing loop to release the automatic switches and at armature 46 releases relays 4:1 and 42.

If a busy condition is encountered in the automatic office during the setting up of the connection, impedance relay 39 in the junction relay set is released and operated intermittently from the busy flash potential in the automatic exchange. This will cause relay 10 of the cord circuit to be operated intermittently by battery over armature 49 of impedance relay 39, armatures 50 and 57, winding of relay 38, conductor 31, tip spring of jack 20, tip spring of plug 19, resting springs of ringing key 15, winding of relay 10 to earth, so that the lamp will flash, and the calling subscriber will also receive busy tone.

It will be noted that when relay 22 is operated, the lamp 21 mounted near the calling device will glow. Hence if the calling device is inadvertently operated when the operator is talking to a subscriber, so as to disconnect the speaking circuit, the operator is advised of this fact by the lighting of the lamp. The speaking circuit can then be restored to normal by the operation of the key 26 which brings down relay 22.

If the operator makes an error while dialling a number, the connection can be released by operating key 26 and the number can then be re-dialled without withdrawing the plug or performing any further operation.

I claim:

1. In a telephone system, a cord circuit for completing connections via a trunk line and automatic switches, a calling device for the cord adapted to intermittently apply a characteristic potential to the two talking conductors of the cord in parallel, and a relay responsive to said applications of potential for transmitting directive impulses over the trunk line to operate the automatic switches.

2. In a telephone system, an operator's cord circuit, a trunk line accessible at one end to the cord and terminating at the other end in an automatic switch, a calling device for the cord adapted to intermittently apply a characteristic potential to the two talking conductors of the cord in parallel, and a relay at said one end of the trunk line responsive to said applications of potential for transmitting directive impulses over the trunk line to operate said switch.

3. In a telephone system, a trunk line terminating in an automatic switch, an operators cord circuit adapted to be connected to the trunk line, a calling device for the cord, means including the calling device for intermittently connecting a characteristic potential to the two talking conductors of the cord in parallel, and a relay controlled by said potential for transmitting impulses over the trunk line to operate said switch.

4. In a telephone system, an operators cord circuit, a trunk line accessible to the cord and terminating in an automatic switch, a calling device for the cord adapted to apply a characteristic potential to both talking conductors of the cord, and a relay at the outgoing end of the trunk line responsive to said potential for controlling the operation of said switch.

In an operators circuit, talking conductors, a battery feeding bridge connected across the talking conductors, a calling device, and means responsive to the calling device being moved from its normal position for short-circuiting said bridge.

6. In an operators circuit, two separate talking conductors, a calling device,means effective when the calling device is moved from its normal position for connecting said talking conductors together, and means controlled by the calling device in returning to its normal position for connecting a characteristic potential to said talking conductors.

7. In a telephone system, an operators cord circuit, battery feeding connections in the cord for supplying talking current to calling and called subscribers, and means for transmitting impulses over said cord while maintaining said battery feeding connections unaltered.

8. In combination, a common battery cord circuit adapted to feed talking battery to calling and called subscribers, a calling de vice, and means for rendering said calling device effective to transmit impulses over said cord circuit while maintaining the normal battery feed connections unaltered.

9. In an operators circuit comprising a connecting link, a telephone set and a calling device,.battery feed and supervisory relays connected to the speaking conductors of the link, a key for connecting the telephone set to the speaking conductors of the link while maintaining the connections of said relays unaltered, and a relay tor transferring the connection of the speaking conductors from the telephone set to the calling device.

10. In an operators circuit comprising a connecting link, a telephone set and a calling device, battery feed and supervisory relays connected to the speaking leads of the link, conductors extending from the link and terminating in the telephone set, a key for connecting said conductors to the speakingleads of the link while maintaining the lUll " continuity thereof.

supervisory connection of said relaystllereto, and a relay for connecting the calling device to said conductors in place off the telephone set.

11. In an operators circuit comprising a cornmon'battery cord terminating in a conneGting plug at each end, a co tinuous talking path extending between the plugs, and means in the operators circuit for transmitting directive impulses over a part of said talking path while maintaining the cord for extending calls via automatic switches, continuous talking conductors extending from the plug to, a battery feed and bridge, a calling device adapted to be connected to the cord, and means including the calling device for transmitting directive impulses .over the talking conductors while maintaining the continuity thereof.

' minating in the calling plug while maintaining the continuity of the talking path, and

' tery connections (ill 13. In a'telephone system, a plug ending cord for extending calls via automatic switches, a continuous talking path com.- prising two inductively connected sections terminating respectively in the answering and calling plugs of the cord, means for transmitting impulses over the section termeans for preventing said impulses from effecting the section terminating in the answering plug.

14:. In an operators circuit comprising two inductively connected sections, battery feeding bridges including supervisory relays normally connected to each section, a calling device adapted to be connected to one section, and means for rendering said calling device efl'ective to transmit impulses over the said one section while maintaining the normal connections to both sections.

15. In a telephone system, a trunk line and a cord circuit adapted to be connected thereto, talking conductors for the cord, bat- I for said talking conductors, a relay forithe trunk line energized in series with one of said battery connections when the cord is connected to the trunk line, anda calling device associated with the cord circuit for intermittently connecting a source of characteristic potential to the talking conductors of the cord to intermittently decnergize said relay. 1

16. In a telephone system, a vlink circuit for completing talking connections between calling and called lines, a calling device, a relay for connecting said calling device with link, an energ zing circuit for said relay n lud n nor a ly ope con -a f h calling device, and a holding elay inc uding normally l sed contacts 10f he calling device- In a telephone system, a link circuit for completing connections between sub:

circuit fo aid scribers, talking conductors for saidlink a calling device, a relay fonconnecting sald calling device to said link, an energizing cirunit for said relay including contacts closed when the calling device is moved from its normal position, and a holding circuit for said relay including normally closed contacts of the calling device anda talking conductor of said link.

18. In a telephone system, a trunk line, a supervisory relay for the trunk line, a link circuit for extending connections to the trunk line, a calling device adapted to be connected to thelink, and means for. shortcircuiting said relay when said calling device is connected tosaid link.

19. In a telephone system, a link circuit for completing connectionsbetween calling and called lines, a calling device, a relay energized initially over a circuit including normany open contact-sot the calling device and held operated over a circuit independent of said contacts for connecting thecall ing device to the link, and a signal controlled by said relay. I

20. In a telephone system, a link circuit for completing'talking connections, battery feed relays for supplying talking current to the link, a calling means for energizing said other. relay to connect the calling device to the link, and means responsive to the operation of said other relay-for locking it operated in series with one of said battery feed relays.

In testimony whereof I have signed at Liverpool, England, this 24th day. of August, 1928.

J H L IS OSTLINE- device, another relay, 

